The present invention relates to an injection produced by dissolving 3-benzoyloxy-1,3,5(10)-estratriene-17-[4-{p-(bis(2-chloroethyl)amino)pheny l}-butanoyloxy]acetate, as an active ingredient, in an ester of iodinated poppy oil fatty acid.
Hitherto, 3-benzoyloxy-1,3,5(10)-estratriene-17-[4-{p-(bis(2-chloroethyl)-amino)phen yl}butanoyloxy]acetate (hereafter referred to as "the present derivative") has been known as an anti-tumor agent which has an unusual properties of accumulating in cancer cells in a large amount but less accumulating in normal cells, is small in side effect and is strong in anti-tumor effect.
However, although the present derivative is oil-soluble, it does not completely dissolve in ordinary oils, and it has not been able to prepare an injection which can fully exhibit the unusual properties of the present derivative.
So far, the present derivative has exhibited its excellent effects as an orally administrable medicine. The orally administrable anti-tumor agent has advantages than (1) its administration is easy and simple and (2) it can be administered at home and there is no need of visiting hospital or being hospitalized to take the medicine. On the other hand, an oral administration of the present derivative is accompanied with some difficulties, namely, increased dosage of the present derivative is necessary because of its decomposition in a digestive tract and its excretion with feces due too its low adsorption rate in an intestines and further, its anti-tumor effect to some cancers is reduced because it can not reach to the cancers in a sufficient amount due to an inadequate passage in vivo.
Accordingly, the appearance of an injection which can fully exhibit its effect has been strongly wanted.
Meanwhile, esters of iodinated poppy oil fatty acid have been known as an oil for arterial injection, which has a property of accumulating in cancer cells to some extent and an injection of anti-tumor agent, such as adriamycin or mitomycin, using the oil as the solvent has been tested with an expectation of reducing its strong side effects, however, it was impossible to bring the expected effect in reality.
As a result of the present inventors' extensive studies on an injection which can exhibit the specific character of the present derivative, testing various oils as solvents, the present inventors have completed the present invention.